"'While I will always remain dedicated to the missions of the department, I informed the president of my decision a few days after the election that Jean and I were eager to return to California,' Chu wrote in a lengthy 'Dear Colleagues' letter Friday morning. 'I would like to return to an academic life of teaching and research but will still work to advance the missions that we have been working on together for the last four years.

"'In the short term, I plan to stay on as secretary past the ARPA-E Summit at the end of February. I may stay beyond that time so that I can leave the department in the hands of the new secretary,' he added."

Chu, who won the Nobel Prize in Physics in 1997, is the latest in a long line of cabinet members to announce they are stepping down.

Update at 11:59 a.m. Statement From Obama:

President Obama issued a statement thanking Chu. He wrote in part:

"As a Nobel Prize winning scientist, Steve brought to the Energy Department a unique understanding of both the urgent challenge presented by climate change and the tremendous opportunity that clean energy represents for our economy. And during his time as Secretary, Steve helped my Administration move America towards real energy independence."

"The journey that I began with you four years ago will continue for many years. I began my message talking about my vision of what I wanted to do with the Department. Some of those goals have been realized, and we have planted many seeds together. Just as today's boom in shale gas production was made possible by Department of Energy research from 1978 to 1991, some of the most significant work may not be known for decades. What matters is that our country will reap the benefits of what we have started."